Printhead mount assembly

ABSTRACT

An apparatus (500) for mounting a printhead (501) relative to a horizontal surface (508). The apparatus (500) comprises an anchor block (502) mounted on the horizontal surface (508); as well as a bottom clamp member (504) and a top clamp member (506) between which the printhead (54) is sandwiched. The bottom clamp member (504) has a first region pivotally attached to the anchor block (502), a central region (530) for contacting at least a part of the printhead (501), and a distal region. The central region (530) of the bottom clamp member (504) is substantially &#34;V&#34; shaped, extends below a plane of the horizontal surface (508), and has an upperside shaped to receive a bottom of the printhead (54). The first region of the bottom clamp member (504) comprises two yoke legs (512) pivotally connected to the anchor block (502). A pivot rod (522) extends between the two yoke legs (512) of the bottom clamp member (504), and the top clamp member (506) is pivotal about the said pivot rod (522).

This application is a continuation application of U.S. patentapplication Ser. No. 07/298,542, filed Jan. 18, 1989, now U.S. Pat. No.4,955,596, issued on 9-11-91.

BACKGROUND

1. Field of the Invention

This invention pertains to the feeding and stacking of items such asstuffed envelopes, and particularly to methods and apparatus for feedingand stacking such items on-edge.

2. Prior Art and Other Considerations

The prior art includes teachings of envelope processing systems whereinenvelopes in a stack are conveyed on-edge in a feed direction toward afeeder for redirecting the envelope toward a singulation gap. Thefeeder, such as an revolving endless belt, for example, contacts asidewall of a lead envelope for directing the lead envelope, in adirection orthogonal to the feed direction, toward the singulation gap.

Prior art envelope processing systems of the type just described haveconsiderable difficulty in handling envelopes of varying thicknesses.Accordingly, significant problems are encountered when the same envelopeprocessing system is expected to run a batch of envelopes which includesboth thick and thin stuffed envelopes. If the singulation gap is sizedfor large envelopes, then a plurality of envelopes ("doubles") might befed essentially simultaneously through the singulation gap. On the otherhand, if the singulation gap is sized for small envelopes, the envelopeprocessing system may fail to direct a thicker envelope toward andthrough the singulation gap.

Envelope processing systems which handle on-edge envelopes also are veryawkward in stacking envelopes after the envelopes have undergone aprocessing (such as character reading or label printing). The potentialinterference with envelopes already-stored in a discharge stack posesproblems for the introduction of an another on-edge envelope into thestack. Such unwelcomed interference is typically occasioned by apotentially obstructive path of envelope travel; by a high degree offriction between envelopes and the stack-defining structure wherein theytravel; and, by difficulty in obtaining and maintaining properregistration of the envelopes introduced into the discharge stack.

In view of the foregoing, an object of the present invention is theprovision of method and apparatus for facilitating the handling ofenvelopes of varying thicknesses by an on-edge envelope processingsystem.

An advantage of the present invention is the provision of method andapparatus for facilitating the feeding of envelopes of varyingthicknesses in an on-edge envelope processing system.

Another advantage of the present invention is the provision of methodand apparatus for facilitating the introduction of processed envelopesinto a discharge stack wherein the envelopes are oriented on-edge.

A further advantage of the present invention is the provision of methodand apparatus for facilitating the smooth and silent stacking of on-edgeenvelopes in a discharge stack wherein envelopes are oriented on-edge.

SUMMARY

An envelope processing system includes an input transport section; aprocessing/transport section; and a discharge transport section.Envelopes are fed on-edge from the input transport section to theprocessing/transport section by a feeder section. The envelopes travelon-edge and one-at-a-time through the processing/transport section whichincludes an optical character reader and a bar code printer. From theprocessing/transport section the envelopes are loaded on-edge onto thedischarge transport section by a stacker section.

In the feeder section, a foremost envelope in an input magazine contactsa feeder and a feed assist device (also known as a "helping hand"). Thefeeder directs the foremost on-edge envelope toward a singulation region(defined by a first pair of rollers, including a driven "pull-out"roller). The singulation region includes a first stage singulation gap(defined between a feed belt and an adjustably-biased singulationmember) and a second stage-singulation gap.

A signal controller monitors when the feeder is having difficulty infeeding an envelope by timing the delay elapsed since the feeding of aprevious envelope. In this respect, if a predetermined number ofenvelopes are not detected as having passed through the singulationregion in a given unit of time, the signal controller presumes that thefeeder is experiencing difficulty in feeding the next article, likelybecause of a greater thickness of the next article. In such a case, thesignal controller enables the feeder to acquire greater contact with thenext envelope by displacing the feed assist device out of its normallybiased co-planar position with the feed belt of the feeder. This is doneby sending a signal to an assist displacement control means, whichsignal causes the displacement of a feeler-switch-borne translatableblock. Movement of the feeler switch away from the feed assist means,and particularly out of contact with a cam surface of a feed assistcarriage, results in the activation of an input transport motor.Activation of the input transport motor resumes incremental advancementof on-edge stacked envelopes toward the feeder and the feed assistmeans, with a resulting greater pressure bearing against thedisplaceable feed assist means. When the bias of the feed assist meansis overcome by such pressure, the feed assist means is displaced furtheraway from a plane of tangency T with the feeder belt, so that the feederbelt has greater contact with the thick envelope. The greater contact ofthe feeder assist means with the thick envelope and the greater pressureurging the contact of the two results in the application of a greaterforce vector on the thick envelope in the direction of the compliantroller pair forming the singulation gap.

The feeder section comprises a selectively revolvable feeder beltentrained about two pulleys, one of the pulleys being a driven/brakedpulley and the other pulley being an idler pulley. A portion of thecourse of travel of the belt lies in a tangent plane T which isessentially parallel to the sidewalls of on-coming envelopes and whichcontacts the sidewall of the foremost envelope in the input magazine.Revolution of the driven pulley causes revolution of the feeder belt,with the frictional contact of the belt with the foremost envelopeserving to direct the foremost envelope toward the singulation gap. Inone embodiment of the invention, the axes of the two rollers comprisingthe feeder are fixed vertical axes. In a second embodiment, the axis ofthe driven roller is a fixed vertical axis, while the vertical axis ofthe idle roller is pivotal about the fixed vertical axis of the drivenroller. In the second embodiment, revolution of the feeder belt causesthe idle roller to pivot, which in turn causes the feeder belt to pivotor kick in towards the foremost envelope, and thereby apply a greatervector force to direct the foremost envelope toward the singulation gap.

The stacker section is downstream from the processing/transport sectionto receive envelopes transported on-edge thereto. The stacker sectionincludes introductory conveying means, stacker conveying means, and adischarge magazine. The introductory conveying means comprises 0-ringpairs which direct an on-edge envelope along an introductory path. Thisintroductory path is oriented at an acute angle with respect to aprocessing path of the processing/transport section. The introductoryconveying means directs an article toward the stacker conveying means,so that a leading edge of the envelope strikes a pair ofvertically-spaced belts forming the stacker conveying means. The stackerbelts follow a triangular course of travel, and define a first linearpath segment and a second linear path segment. In directing an envelopealong the first linear path segment, the stacker conveying means causesthe envelope to be deflected through an obtuse angle with respect to theintroductory path.

In the following the first linear path segment defined by the stackerconveying means, the leading edge of an envelope is directed to a vertexof the stacker belt triangular path for interposition between apreviously stacked envelope and the stacker belts. That is, as theleading edge of the envelope reaches a pulley forming a vertex of thetriangular path, the leading edge is interposed between the midsectionof the previously stacked envelope and the stacker belts at a bend pointwhereat the stacker belts turn at an obtuse angle to define a secondlinear path segment. This second linear path segment is thus the secondleg of the triangular path.

As a leading envelope edge rounds the bend point and travels up thesecond linear path segment between the stacker belts and the previouslystacked envelope, the trailing edge of the envelope "fishtails" (i.e.,is deflected) through an angle which is acute with respect to the firstlinear path segment. The fishtailing is prompted by the geometricalconfiguration of the path traveled by the envelope at the bend point,and is further facilitated by the operation of a rotatable positioningelement.

In the above regard, an elongated rotatable positioning element isprovided in the plane of the discharge magazine. The positioning elementis basically threaded along a first portion thereof with the helicalthreads extending just slightly above the plane of the dischargemagazine. The rotating threads of the positioning element catch thebottom of trailing edges of envelopes and displace the trailing edges atleast partially through the fishtail angle.

As envelopes travel along the second linear path segment the leadingedges thereof strike an abutment wall forming the discharge magazine.The abutment wall has an interior cavity which is filled with acousticinsulating material, so that contact of the leading edge does not resultin an audibly loud pop.

As the number of envelopes increases in the discharge magazine, thestack of envelopes in the discharge magazine exerts pressure, throughthe most recently stacked envelope, against a pressure sensor. Thepressure sensor has a pivotal sensor arm which extends through a gap inthe two vertically spaced belts forming the stacker conveying means.When the envelope pressure in the stack overcomes a biasing force on thesensor arm, the sensor contacts a microswitch, which in turn activates adischarge transport motor to carry on-edge envelopes away from thestacker section.

As the envelopes travel away from the stacker section,vertically-oriented ridges on the abutment wall serve as bearing pointsto reduce frictional drag between the abutment wall and leading edges ofthe envelopes. Moreover, envelopes are registered against the abutmentwall by the operation of a second portion of the rotatable positioningelement. In this regard, the second portion of the rotatable positioningelement has arcuate surfaces thereon which periodically extend above theplane of the magazine floor, and thereby slightly elevate the trailingedge of the envelope, so that the envelopes experience a force vectortoward the abutment wall.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments as illustrated in the accompanyingdrawings in which reference characters refer to the same partsthroughout the various views. The drawings are not necessarily to scale,emphasis instead being placed upon illustrating the principles of theinvention.

FIG. 1 is a front isometric view showing a feeder and stacker apparatusaccording to an embodiment of the invention;

FIG. 2 is a top view of a feeder section of the feeder and stackerapparatus of the embodiment of FIG. 1;

FIG. 3 is a front view of a feeder assist device of the feeder of theembodiment of FIG. 1;

FIG. 4 is a side view of an assist displacement control device of thefeeder section of the embodiment of FIG. 2 taken along the line 4--4;

FIG. 5 is a top view of a stacker section of the feeder and stackerapparatus of the embodiment of FIG. 1;

FIG. 6 is a front cross-sectional view of a discharge magazine takenalong the line 6--6 of the stacker section of the embodiment of FIG. 5;

FIG. 7 is a front isometric view showing portions of introductoryconveying means and stacker conveying means included in the stackersection of the embodiment of FIG. 5;

FIGS. 8A-8E are schematic top views showing successive stages of travelof a flat article through the stacker section of the embodiment of FIG.5;

FIG. 9 is a partial top view of a feeder belt assembly of a feedersection according to another embodiment of the invention;

FIG. 10 is a schematic view showing the relationship of a roller and ahorizontal belt of the embodiment of FIG. 1;

FIGS. 11A and 11B are schematic views showing a feeder assist device ofthe embodiment of FIG. 1 in a normally biased position and in adisplaced position, respectively;

FIG. 12 is a schematic view showing the displacement of a feeder beltaccording to the embodiment of FIG. 9;

FIG. 13A is a side view of an adjustable read window device according toan embodiment of the invention;

FIG. 13B is a front view of the adjustable read window device of FIG.13B;

FIG. 13C is a top view of the adjustable read window device of FIG. 13A;

FIG. 14 is a front view of a read window set-up guide according to anembodiment of the invention;

FIG. 15A is a top view of a printhead mount assembly according to anembodiment of the invention;

FIG. 15B is a side view of the printhead mount assembly of FIG. 15A;

FIG. 16 is a top view of means for defining a first singulation stage ofthe feeder of the embodiment of FIG. 1; and,

FIG. 17 is a partial side view of the means for defining a firstsingulation stage of the embodiment of FIG. 16 taken along line 17--17.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a system 20 for processing flat articles, such asenvelopes. System 20 comprises an input transport section 22; aprocessing/transport section 24 wherein flat articles, such asenvelopes, are transported along a processing path 26; and, a dischargetransport section 28. The processing system 20, hereinafter alsoreferred to as an envelope processing system 20, also includes akeyboard 32; a monitor 34; and, a printer 36.

Envelopes are fed on-edge from the input transport section 22 to theprocessing/transport section 24 by feeder section 40. The envelopestravel on-edge and one-at-a-time through the processing/transportsection 24. From the processing/transport section 24 the envelopes areloaded onto the discharge transport section 28 by stacker section 38.

The direction of envelope travel on the input transport section 22 isshown by arrow 42; the direction of envelope travel from section 22 ontothe processing/transport section 24 as propelled by the feeder section40 is shown by arrow 44; and, the direction of envelope travel on thedischarge transport section 28 is shown by arrow 45. The direction ofenvelope travel on the processing/transport section 24 is perpendicularto the direction of envelope travel on the input transport section 22and the discharge transport section 28.

In the particular embodiment under discussion, the processing/transportsection 24 directs envelopes along the processing path 26 which hasreader means 50; a detector photocell 52; and bar code printer means 54positioned therealong. It should be understood that in other embodimentsof the invention, other and/or additional functions can be performedalong the processing path 26.

In the embodiment illustrated in FIG. 1, the reader means 50 includes anoptical character recognition (OCR) read head 56 and associatedelectronics for reading alphanumeric information on the sidewall of anon-edge envelope and for generating signals indicative thereof. The barcode printer means 54 includes an ink jet (IJ) printer nozzle 60 andassociated ink jet electronics for applying a bar code to the sidewallof an on-edge envelope transported by the nozzle 60. In the illustratedembodiment, the bar code printer means 54 is a Videojet III Bar CodePrinter provided by Videojet Systems International.

Envelopes are transported on-edge through the processing/transportsection 24 in the direction of arrow 44 by a transport system 62 whichincludes a series of revolving horizontal belts 64 and a series ofrevolving vertical belts, including front vertical belts 66 and backvertical belts 68. The bottom edges of envelopes ride on the horizontalbelts 64, while the front sidewalls and back sidewalls of the envelopesare contacted by the belts 66 and 68, respectively.

STRUCTURE: FEEDER SECTION

As shown in FIG. 2, the feeder section 22 of the envelope processingsystem comprises an input magazine 70; feeding means, such as feeder 72;means for defining a singulation region 73, including first stagesingulation means 74 and second stage singulation means (includingrollers 75 and 76); feed assist means 80 (also known as a "helpinghand"); feed interval detection means 82; and, assist displacementcontrol means 84. As will hereinafter be described, envelopes in theinput magazine 70 (shown as envelopes 86A through 86N in FIG. 2) aresequentially advanced on-edge to feeder 72. The feeder 72 directs aleading flat envelope in the input magazine 70 (envelope 86A) in a feeddirection (indicated by arrow 88) toward the singulation region 73 fromwhence the envelope 86A is further conveyed along the processing path26.

The input magazine 70 comprises a magazine frame 100 having a horizontaltop surface 102. Standing vertically on the magazine surface 102 is anenvelope guide wall 101 which extends along the input transportdirection (shown by arrow 42) near the left edge of frame 100. A similarwall 104 is provided near the right edge of frame 100. Two posts 106Aand 106B also stand erect on the magazine surface 102 near the envelopeguide wall 104. Although equipment housing 107 hides post 106B in FIG.1, FIG. 2 shows housing 107 removed and post 106B exposed. A guide rod108 has a first end thereof connected to the post 106A and a second endthereof connected to the post 106B, so that guide rod 108 is held aloftand extends parallel to the input transport direction 42.

The input magazine 70 also includes input transport means 110 fortransporting envelopes on-edge to the feeder 72. The input transportmeans 110 comprises three endless transport belts 112A, 112B, and 112Chaving upper courses of travel which extend over the magazine topsurface 102. Each of the transport belts 112 is entrained about acorresponding driven pulley 114 (situated under magazine top surface 102near an entrance end of the input magazine 70) and a corresponding(unillustrated) idler pulley, so that the transport belts 112 travel inthe input transport direction 42. The driven pulleys 114A, 114B, and114C are commonly mounted on rotatable shaft 116. Rotatable shaft 116 isdriven by input transport motor 118, which provides power to rotate thepulleys 114A, 114B, 114C for propelling the transport belts 112A, 112B,112C and the envelopes carried thereon, toward the feeder 72.

In the illustrated embodiment, each of the transport belts 112A, 112B,112C is an elastomeric timing belt having teeth 120 provided thereon atregularly spaced intervals. Between adjacent ones of the teeth 120 is atrough 122. So configured, the belts 112A, 112B, 112C with teeth 120 andtroughs 122 are well suited to engage bottom edges of the envelopescarried on-edge thereon.

The input magazine 70 also includes a compression plate 124. Compressionplate 124 has a hollow sleeve member 126 which fits over the guide rod108, so that compression plate 124 is rotatable about guide rod 108(away from the magazine top surface 102) and is translatable along guiderod 108 (along the input transport direction 42). Compression plate 124is essentially a rectangular flat plate which, when left in its ordinaryorientation, extends across the top surface 102 of the input magazine 70in a direction perpendicular to the direction 42 of transport, restingon the tops of the transport belts 112A, 112B, 112C. As will be seenhereinafter, when the transport belts 112A, 112B, 112C are incrementallydriven in the input transport direction 42, the compression plate 124,resting on transport belts 112A, 112B, 112C, is also advanced toward thefeeder 72, with the result that envelopes between the plate 124 and thefeeder 72 are compressed further toward the feeder 72.

The feeder 72 of the embodiment of FIG. 2 comprises an endless beltentrained about feeder rollers 132 and 134. Both feeder rollers 132 and134 are mounted to rotate about respective stationary vertical axes.Feeder roller 132 is connected (below the plane of surface 102) by drivebelt 136 to a clutch/brake mechanism 138. Clutch/brake mechanism 138 isin turn connected by belt 139 to feeder motor 140. When the feeder motor140 is activated and the clutch brake is energized, the first feederroller 132 rotates about its vertical axis in the direction shown byarrow 141, thereby imparting clockwise momentum to the endless belt 130entrained about rollers 132 and 134. Roller 134 is an idle roller, whichrotates about its vertical axis as endless belt 130 moves in itsclockwise direction. As described hereinafter, as the endless belt 130moves in the clockwise direction, the endless belt 130 contacts a firstsurface (i.e., a first sidewall) of the leading envelope 86A in theinput magazine and exerts a force vector on the envelope 86A in the feeddirection (shown by arrow 88), with the result that belt 130 impartsmomentum to envelope 86A toward the singulation region 73.

As indicated above, the singulation region 73 comprises a first-stageand a second stage. A first stage singulation gap 142, seen in FIG. 16,is defined between the first stage singulation means 74 and the belt 130of feeder 72. A second stage singulation gap 143 is defined between therollers 75 and 76.

The first stage singulation means 74 includes disc-shaped singulationstones 144A and 144B. The singulation stones 144A and 144B are securedto opposite ends of a vertical shaft 145 which extends through thecenters of the stones 144A and 144B. Shaft 145 is, in turn, carried by alever arm 146. The lever arm 146 pivots about studs 147A and 147B. Studs147A and 147B are mounted to the horizontal magazine surface 102. Thelever arm 146 pivots about studs 147A and 147B through link members 148Aand 148B and associated link pins 149A and 149B.

The lever arm 146 carries a rotatable nylon roller 150. The nylon roller150 is rotatably mounted on a second vertical shaft 151. The shaft 151is carried on lever arm 146 so that the axis of shaft 151 and roller 150are closer to the feeder 72 (in the sense of the direction of arrow 42)than are shaft 145 and the axis of stones 144A and 144B; and so that theaxis of shaft 151 and roller 150 is more upstream (in the sense of thedirection of arrow 88) than are shaft 145 and the axes of stones 144Aand 144B. With the shafts 145 and 151 so positioned, the periphery ofroller 150 is further upstream (in the sense of the direction of arrow88) than are the peripheries of stones 144A and 144B.

The first stage singulation means 74 is biased in the direction of thefeeder 72 (i.e., in the direction of arrow 42) by biasing means 152.Biasing means 152 comprises biasing spring 153, a first end of which issecured to the lever member 148A and a second end of which is secured toanchor block 154. Anchor block 154 is in turn secured to the horizontalmagazine surface 102. Anchor block 154 carries a threaded adjustmentscrew 155. The adjustment screw 155 has a head which bears against anextended portion of link member 148A. The relative position of the headof adjustment screw serves as a limit for the biasing means 152, andthus controls the width of the first singulation gap 142.

In the vicinity of the stones 144A, 144B the lever arm 146 carriestwo-wing members 156A, 156B. Wing members 156A, 156B straddle the roller76 and thus prevent thin envelopes from wrapping around the roller 76 inthe reverse direction.

Turning now to the second stage singulation gap 143, the roller 76 is acompliant roller having a circumferential surface that touches roller75. Both rollers 75 and 76 are rotatable about corresponding fixedvertical axes. As shown in FIG. 2, roller 75, also known as the"pull-out" roller, is oriented so that its circumferential surfacecontacts the first flat side of an envelope 86 as the envelope 86 goesthrough the second stage singulation gap 143. Roller 76, positioned justacross gap 143 from roller 75, is oriented so that its circumferentialsurface contacts the second, or opposite, side of the envelope 86.

Downstream from the rollers 75 and 76 along the feed direction(indicated by arrow 88) is a second pair of rollers, particularly thirdroller 157 and fourth roller 158. Like rollers 75 and 76, rollers 157and 158 are oriented for rotation about fixed vertical axes. Roller 157is situated to contact the first side of envelope 86; roller 158 issituated to contact the second side of envelope 86.

Roller 157 is continuously rotationally driven in the clockwisedirection by virtue of its connection (via belt 159) to motor 160. Therotational motion of roller 157 is transmitted to pull-out roller 75 bybelt 161 so that roller 75 rotates in the clockwise direction.

In the embodiment of FIG. 2, the roller 76 is connected via belt 162 andslip clutch 164 (positioned beneath roller 76) to the power drive forroller 157. As described hereinafter, in the event a tendency for amultiple feed is detected, the roller 76 can be rotated in the clockwisedirection to repel any second envelope (such as envelope 86B in FIG. 1)that might attempt to simultaneously enter the second stage singulatorgap 143, along with the leading envelope (i.e., envelope 86A). Inanother unillustrated embodiment, the roller 76 is merely an idlerroller which is not connected to roller 157.

Two detectors are positioned downstream from the singulation gap 78,particularly singulator blockage detector 170 and singulator clearancedetector 172. The singulator blockage detector 170 comprises photocelltransmitter 174 and photocell receiver 176 oriented to direct a beam 178transverse to the direction of feed transport 88. The beam 178 crossesthe direction of feed transport 88 at a point downstream from rollers 75and 76 whereby, when a leading edge of an envelope trips the beam 178,an envelope is travelling through the second stage singulator gap 143.

The singulation clearance detector 172 comprises photocell transmitter180 and photocell receiver 182 oriented to direct a beam 184 transverseto the direction of feed transport 88. The beam 178 crosses thedirection of feed transport 88 at a point downstream from rollers 157and 158.

The photocell receivers 176 and 182 are connected by lines 186 and 188,respectively, to input ports of a signal controller 190. The signalcontroller 190 has output ports connected by lines to various devicescontrolled thereby, including line 192 connected to the clutch/brakemechanism 138 associated with feeder 72. As indicated by its descriptionhereinafter, to the extent utilized by the present invention, the signalcontroller 190 basically serves to time the application of signals tothe mechanisms controlled thereby, and thus comprises conventionalcircuitry well understood by the man skilled in the art.

In one embodiment, the signal control receives signals from the readermeans 50 as an indication of the frequency of envelopes clearing thesingulator region 23, rather than receiving signals from the singulatorclearance detector 172.

The transport system 62 of the processing/transport section begins inthe neighborhood of the singulator clearance detector 172. That is, therotatable horizontal belt 64 and the vertical belts 66 and 68 arepositioned to catch articles fed from between roller pair 150, 152 andto direct the articles along the processing/transport section 24 in thedirection of arrow 44.

The feed assist means 80, also known as the "helping hand", includes afeed assist carriage 200 that comprises an essentially cylindricalmember 202. The major cylindrical axis of cylindrical member 202 isparallel with the input transport direction 42. A first end of thecylindrical member 202 has a rectangular plate member 204 fastenedthereto. Plate member 204 lies in a plane orthogonal to the majorcylindrical axis of cylindrical member 202. A second end of thecylindrical member 202 has a pair of cam surfaces 206 and 208 formedthereon. As shown in FIG. 2, cam surface 206 is a planar surface that isessentially orthogonal to the magazine top surface 102. As seen in FIG.4, cam surface 208 is a planar surface that is angularly inclined withrespect to the magazine top surface 102. At its second end near camsurface 208, the top of the cylindrical member is slightly beveled as at209 to be essentially parallel with the horizontal.

The cylindrical member 202 and the rectangular plate member 204comprising the feed assist carriage 200 have an aligned apertureextending therethrough which loosely accommodates the guide rod 108,whereby the feed assist carriage 200 is translatable to and fro alongthe guide rod 108 in the input transport direction indicated by arrow42. The rectangular plate member 204 of the carriage 200 has a pin 210anchored therein. A first end of a biasing spring 212 securely engagespin 210. A second end of the biasing spring 212 securely engages asimilar pin 214 anchored in the envelope guide wall 104, with the resultthat biasing spring 212 tends to pull the feed assist carriage 200toward a blunt stop end 216 of the envelope guide wall 104. The stop end216 of envelope guide wall 104 serves as a stop for limiting the degreeof travel of the feed assist carriage 200 in the direction which is thereverse of the input transport direction 42.

As shown in FIGS. 2 and 3, the feed assist means 80 has a plurality ofenvelope-contacting rollers provided thereon. In particular, the feedassist means features roller pair 220A and 220B mounted on vertical post221; roller pair 222A and 222B mounted on vertical post 223; roller pair224A and 224B mounted on vertical post 225; and, roller pair 226A and226B mounted on vertical post 227. The posts 221, 223, 225, and 227 areheld aloft by affixation near their midpoints to a cross beam 230. Eachroller is rotatable on its respective post, but is held captive thereonby retaining rings, such as retaining rings 232A and 232B shown on post227 in FIG. 3. Cross beam 230 is anchored into rectangular plate member204 of the feed assist carriage 200, and is retained therein by setscrews 234.

Near its midpoint, the cross beam 230 of the feed assist carriage 200 issupported by a vertical leg 240 that has a wheel 242 rotatably mountedat the distal end thereof. Wheel 242 rides on the input magazine topsurface 102.

A feeder switch 244 is positioned so that a feeler arm 245 thereof canride on cam surface 206 of the feed assist carriage 200 under normaloperating conditions, i.e. when the feeder 72 should be intermittentlyfeeding envelopes 86 toward the singulator gap 78. The feeder switch 244is connected by line 246 to the signal controller 190. The signalcontroller 190 is connected by line 247 and 248 to the feeder motor 142and to the roller motor 156, respectively.

The assist displacement control means 84 comprises means for changingthe degree of pressure bearing against the feed assist means 80, and inparticular comprises switch carriage means 250. As shown in FIGS. 2 and4, switch carriage 250 is an essentially rectangular block 252 thatcarries a switch 254 on support bracket 256. Switch 254 is carried oncarriage 250 so that a feeler arm 258 included in the switch 254 canride on the cam surface 208, or on the beveled top surface 209 of thefeeder assist carriage 200. The switch 254 is connected by electricalline 260 to the motor 118 of the input transport means 110.

As mentioned before, the guide rod 108 extends from post 106A near theentrance to the input magazine 70 to post 106B near the rear of theapparatus. Post 106B also carries a rear end of second guide rod 262. Afront end of second guide rod 262 is anchored in the envelope guide wall104 near stop end 216 thereof. As shown in FIG. 4, the second guide rod262 is directly beneath, but considerably lower in elevation than, theguide rod 108. The feed assist carriage 200 rides sufficiently aloft onthe guide rod 108 so that the second guide rod 262 poses no obstacle forthe movement of the carriage 200.

The rectangular block 252 of the switch carriage 250 has aperturesprovided therein for receiving the upper guide rod 108 and the lowerguide rod 262, and for permitting the rectangular block 252 to translatein the directions shown by double-headed arrow 264.

Near its top, the rectangular block 252 of switch carriage 250 has achannel 266 formed therein. The channel 266 is bridged by a cross member268. The cross member 268 has a clevis 270 rotatably secured thereto. Adistal end of the clevis 270 is anchored in a first side of a couplingblock 272. A second side of the coupling block 272 is connected to anoutput piston 274 of a stepper motor 276. The output piston 274 ofstepper motor 276 is of the type that extends and retracts in thedirection of arrow 264 in accordance with signals produced by thestepper motor 276. The stepper motor 276 is mounted on the post 106B.The post 106B has an aperture formed therein to accommodate the outputpiston 274 of stepper motor 276, so that the output piston 274 canconnect to the coupling block 272. As shown in FIG. 2, input terminalsof the stepper motor 276 are connected by line 278 to output ports ofthe signal controller 190. Line 278 carries signals thereon whichdictate whether the output piston 274 of stepper motor 276 is to extendor retract, and thus whether the switch carriage 250 is to travel towardor away from the input magazine 70.

It will be seen hereinafter that the assist displacement control means84, including the switch carriage 250 and the input transport means 110connected thereto, serves to control the displacement of the feed assistmeans 80 by changing the degree of pressure bearing against the feedassist means 80. The signal controller 190 determines whether theposition of the feed assist means 80 should be changed by examining thetime elapsed since the last feed of an envelope through the singulatorregion 73. If that elapsed time exceeds a predetermined time, thestepper motor 276 retracts the switch carriage 252. With retraction ofthe switch carriage 252, the motor 118 of the input transport means 110is energized, with the result that envelopes are further advanced towardthe feed assist means 80, thereby pushing the feed assist means 80further in the direction of the input transport direction 42.

The feeder 72' of the embodiment of FIG. 9 differs from the feeder 72 ofthe embodiment of FIG. 2 in several respects. Unlike the roller 134 ofthe FIG. 2 embodiment, roller 134' of FIG. 5 does not have a fixedvertical axis about which it rotates. Rather than being anchored to thesurface 102, the vertical axis 280 of roller 134' is freely suspendedabove the surface 102, with the result that the entire assemblycomprising rollers 132', 134', and endless belt 130', can pivot or swingabout vertical axis 282 in the direction of arrow 284. The pivoting ofthe feeder assembly in this manner results from the force vectoroccasioned by the revolution of endless belt 130' Accordingly, the belt130' swings beyond its former position (shown as plane 286 in FIG. 9)and toward the leading envelope in the input magazine 70.

The feeder 72' of the embodiment of FIG. 9 also further includes biasingmeans 288 for biasing the roller 134' so that the axes 282 and 280 ofrollers 132' and 134' are in the plane (plane 290 being parallel toplane 286). The biasing means 288 includes a bracket 292 upon whichroller 134' is rotatably mounted. Bracket 292 is urged toward a verticalpost 293 by a spring 294.

The feeder 72' of the embodiment of FIG. 9 also includes means forlimiting the degree of pivotal motion of the feeder 72' away from plane286. In this regard, the bracket 292 carries an adjustment screw 295thereon. The head of adjustment screw is aligned with a vertical stopmember 296. The size of the gap 297 separating the head of adjustmentscrew 295 and the stop member 296 when the feeder 72' is braked is equalto the maximum component (along the direction of input transport) of thedisplacement of feeder 72' from the plane 286. Thus, distance 297 equalsdistance 298.

STRUCTURE: STACKER SECTION

As shown in FIG. 5, the stacker section 38 of the envelope processingsystem comprises a discharge magazine 300; introductory conveying means302; stacker conveying means 304; and, means 306 for displacing atrailing edge of a flat article. The stacker section 38 of the envelopeprocessing system is downstream from the processing/transport section 24to receive envelopes transported on-edge thereto by the transport system62 of the processing/transport section 24. FIG. 5 shows how thehorizontal belt 64 and the vertical belts 66 and 68 of the transportsection 62 transport belts toward the stacker section 38.

The stacker section 38 has a horizontal stacker floor surface 310 whichis at substantially the same elevation as both the feeder magazinesurface 102 of the feeder section 40 and the plane of the upper courseof travel of the horizontal belt 64 of the processing/transport section24. As will be described hereinafter, the introductory conveying means302 and the stacker conveying means 304 of the stacker section 38 areprimarily positioned above the stacker floor surface 310, with drivingelements thereof being located beneath the surface 310.

The discharge magazine 300 comprises a magazine floor 320; magazineabutment means 322; and, article discharge transport means 324. Thedischarge magazine floor 320 is co-planar with the stacker floor surface310. The magazine abutment means 322 is vertically mounted on themagazine floor 320 along the left-most edge thereof as seen in FIGS. 5and 6, and thus has an axis of elongation 325 that extends parallel tothe direction of discharge transport as indicated by arrow 45.

The discharge magazine abutment means 324 carries two verticallyupstanding posts, particularly posts 326A and 326B (only post 326B beingillustrated in FIGS. 5 and 6. Posts 326A and 326B function in analogousmanner to posts 106A and 106B of the feeder section 40, i.e., to holdaloft a horizontal guide rod. Thus, posts 326A and 326B hold aloft guiderod 328. As described hereinafter, guide rod 328 serves essentially thesame type of function as does guide rod 108 of the feeder section 40,and in particular serves as a guide for compression plate 330.

As shown in both FIGS. 5 and 6, the discharge magazine abutment means322 is an elongated plate member which has a first exterior wall 332 anda second exterior wall 334, both exterior walls 332 and 334 extendingparallel to the axis of elongation 325. As shown in FIGS. 5 and 6, thefirst exterior wall 332 faces toward the right and is contactable byenvelopes, while the second exterior wall 334 faces toward the left. Theexterior walls 332 and 334 define an elongated central cavity 336therebetween, which, as best shown in FIG. 6, is filled with acousticinsulation material.

As also shown in FIG. 6, the first exterior wall 332 of the magazineabutment means 322 has a plurality of parallel, horizontally extendingridges 340 along the length thereof. As described hereinafter, theridges 340 of the exterior wall 332 are contactable by envelopes beingtransported in the discharge magazine 330 and serve as bearing points todecrease frictional drag between the envelope edges and the abutmentmeans 322.

The article discharge transport means 324 of the discharge magazine 300resembles the input transport means 110 of the feeder section 40. Inthis regard, the discharge transport means 324 comprises three transportbelts 342A, 342B, and 342C which have upper courses of travel that lieessentially in, or just above, the plane of the magazine floor 320.Although the drive mechanism of the transport belts 340 is not fullyshown, it should be understood that, like the belts 112A, 112B, 112C offeeder section 40, the transport belts 342A, 342B, 342C entrain pulleysthat are commonly driven by motor 343. Moreover, the belts 342A, 342B,342C, like the belts 112A, 112B, 112C, are elastomeric timing beltshaving teeth 344 provided thereon at regularly spaced intervals.

As mentioned above, the compression plate 330 of the stacker section 38travels along the guide rod 328 in like manner as compression plate 124travels along guide rod 108. To this end, the compression plate 330 hasa sleeve 345 which fits over and is rotatable about the guide rod 328.When in its natural orientation, the bottom edge of the compressionplate 330 rides on the transport belts 342 for travel away from thestacker section 38 in the direction depicted by arrow 45. Thecompression plate 330 thus forms a surface against which a sidewall of afirst flat article, once it is discharged from the stacker section 38,can vertically contact.

The introductor conveying means 203 of the stacker section 38 comprisestwo pairs of revolving vertically oriented O-rings, particularlyintroductory front rings 350A and 350B and introductory rear rings 352Aand 352B. The introductory front rings 350A and 350B are each entrainedabout vertically upstanding pulleys 354 and 356, while the introductoryrear rings 352A and 352B are each entrained about vertically upstandingpulleys 358 and 360.

As shown in FIGS. 6 and 7, the O-ring pair 350A, 350B is entrained aboutthe same pulley 354 as is the front vertical belt 66 of theprocessing/transport section 24. To accommodate the common entrainment,belt 66 extends around a midportion of the pulley 354, while the O-ring350A extends around a top portion of the pulley 354 and the O-ring 350Bextends around a bottom portion of the pulley 354. The O-ring pair 352is similarly entrained along with rear vertical belt 68 on the pulley358. Although not shown, it should be understood that pulleys 354 and356 are continuously driven by motors in the same manner as are otherpulleys and rollers described herein, which motors are positionedbeneath the stacker floor surface 310.

As shown in FIG. 5, the pulleys 356 and 360 are so positioned that theO-ring pairs 350, 352 direct flat articles travelling on-edgetherebetween along a linear introductory path indicated by broken line360. As seen from above in FIG. 5, the linear introductory path 360 isoriented at an acute angle 362 with respect to the direction (indicatedby arrow 44) of transport through the processing/transport section 24.The O-ring pairs 350, 352 comprising the introductory conveying means302 thus direct articles travelling on-edge therebetween so that aleading edge of each article contacts the stacker conveying means 304.

The stacker conveying means 304 includes a pair of stacker belts 370A,370B which serve to direct articles travelling on-edge to the dischargemagazine 300. Each stacker belt 370A and 370B extends around a trio ofvertically upstanding rotatable pulleys 372, 374, and 376. The stackerbelt 376 is rotatably driven in the clockwise direction by virtue of itsconnection (via belt 377) to motor 378. Accordingly, the pulleys 374 and376 also rotate in the clockwise direction, and the stacker belts 370travel in the clockwise sense about the pulleys they entrain.

Each of the pulleys 372, 374, and 376 are mounted on the stacker floorsurface 310, so that their axes of rotation are perpendicular to thefloor surface 310. As shown in FIG. 7, stacker belt 370A extends arounda top portion of the pulleys while stacker belt 370B extends around atop portion of the pulleys, thereby providing a gap 379 between thestacker belts 370A and 370B.

As shown in FIG. 5, the pulleys 372, 374, and 376 are positioned so thatthe stacker belts 370 acquire an essentially triangular course of travelabout the pulleys. As part of this triangular course of travel, thestacker belts 370 direct articles delivered thereto along a first linearpath segment (indicated by broken line 380) toward a midsection, such asmidsection 382 of envelope 384A, of a previously stacked article indischarge magazine 300. As used herein, the midsection of an articlemeans a section of the article proximate the pulley 374 after thearticle has just been stacked in the discharge magazine 300. As shown inFIG. 5, the first linear path segment 380 formed by the stacker belts370 extends between pulleys 372 and 374, and is oriented at an obtuseangle 386 with respect to the linear introductory path 360 provided bythe introductory conveying means 302.

As another part of the triangular course of travel, the stacker belts370 define, between pulleys 374 and 376, a second linear path segment(indicated by broken line 388). As shown in FIG. 5, the second linearpath segment 388 is oriented at an obtuse angle 390 with respect to thefirst linear path segment 380. The first linear path segment 380 and thesecond linear path segment 388 intersect at a bend point 391. At bendpoint 391 the tangent of the stacker belts 370 relative to pulley 374 isessentially orthogonal to the direction of discharge conveyance 45.

As described hereinafter, when a flat article such as an envelope isconveyed by the stacker belts 370, the leading edge of the article isinitially directed along the first linear path segment 380 to themidsection 382 of a previously stacked article. Upon reaching midsection382 and pulley 374, the leading edge of the article bends through theobtuse angle 390 as the article becomes interposed between the stackerbelts 370 and the previously stacked article, by virtue of the stackerbelts 370 directing the article along the second linear path segment388. As the leading edge of the article is so bent around the pulley374, the trailing edge of the article is displaced through the angle392, with the result that the trailing edge of the article essentially"fishtails" away from the first linear path segment 380.

The fishtailing, or angular displacement, of the trailing edge of a flatarticle in the manner just described is further facilitated bypositioning element 394. Positioning element 394 is a rotatable elementhaving a major axis of rotation 396. The axis of rotation 396 extendsparallel to the axis of elongation 325 of the abutment means 322, andhence is essentially parallel to the discharge direction indicated byarrow 45. The axis of rotation 396, as sen in FIG. 6, is just slightlybeneath the floor 320 of the discharge magazine 300. The floor 320 ofthe discharge magazine 300 has an elongated slot formed therein toaccommodate the positioning element 394.

The axis of rotation 396 of the rotatable element 394 is separated by adistance 400 from the axis of elongation 325 of the abutment means 322.Since the axes 396 and 325 are parallel, the distance 400 is understoodto be the perpendicular distance between those two axes. The bend point391 is separated from the axis of elongation 325 of the abutment means322 by a distance 402. As shown in FIG. 5, the distance 400 is greaterthan the distance 402, which means that the axis of rotation 396 of thepositioning element 394 is separated from the axis of elongation 325 ofthe abutment means 322 by a greater distance than is the midpoint 382 ofa flat article at the bend point 391.

The positioning element 394 includes a first portion 394A and a secondportion 394B. The first portion 394A has exterior threads 404 thereonwhich extend slightly above the plane of the magazine floor 320 toengage bottom edges of flat articles. The second portion 394B has aplurality of chord-like surfaces 406A, 406B, and 406C formed on theexterior thereof. Between the chord-like surfaces 406 are providedarcuate surfaces 408A, 408B, and 408C. When the chord-like surfaces 406are parallel to the magazine floor 320, the surfaces 406 essentially liein the plane of the magazine floor 320. However, when the chord-likesurfaces 406 are not parallel to the magazine floor 320, the arcuatesurfaces 408 on the periphery of the second portion 394B extend slightlyabove the plane of the magazine floor 320. As shown in FIG. 6, when anarcuate surface 408 extends above the plane of the magazine floor 320,the bottom edge of a flat article resting thereon is displaced, orslightly elevated, above the magazine floor 320 through an angle 410.Elevating an article in this manner permits the leading edge of thearticle to fall by gravity toward the abutment means 322 for betterregistration thereagainst.

The positioning element 394 rotates about its axis of rotation 396 byvirtue of its connection to a rotating shaft of motor 414. As shown inFIG. 5, motor 414 is located beneath the magazine floor 320.

The positioning element 394 is situated closer to the bend point 391then are the discharge transport belts 342. That is, with respect to thedirection of discharge as depicted by arrow 45, the distance 416separating the positioning element 394 from the bend point 391 is lessthan the distance 418 separating the discharge belts 342 from bend point391. Thus, the first portion 394A of the positioning element 394 isoptimally located to engage trailing edges of flat articles as thearticles are interposed between a previous article in the stack and thestacker belts 370 along the second linear path segment 388.

As mentioned above, the gap 379 is provided between the stacker belts370A and 370B. The gap 379 is sized to accommodate the O-ring 352A ofthe introductory conveying means which, as shown in FIG. 5 must extendinto the interior of the triangular course of travel of stacker belts370.

The stacker section 38 also includes a stack sensor means 420 forcontrolling the discharge transport means 324, particularly thetransport belts 342. The stack sensor means 420 comprises a horizontalsensor lever arm 422 that is carried by a vertically upstanding pivotpost 424. Pivot post 424 is mounted on the stacker floor surface 310 sothat the lever arm 422 can pivot thereabout. The lever arm 422 has afirst end 422A and a second end 422B. The first end 422A of the sensorlever arm is resiliently biased in the counter-clockwise direction withrespect to pivot post 424 by virtue by biasing means 426. In theillustrated embodiment, biasing means 426 is a spring having a first endwhich engages the first end 422A of the sensor lever arm and a secondend which is secured to a vertically upstanding stationary post 428. Thebiasing means 426 serves to urge the sensor lever arm 422 in thecounter-clockwise direction away from a microswitch 430. Microswitch 430is connected by an unillustrated electrical lead to the drive motor 343for the discharge transport belts 342A, 342B, 342C. Stop member 430provides a limit to the extent of counter-clockwise rotation about thepivot post 424.

The second end 422B of the sensor lever arm extends through the gap 379provided between the stacker belts 370A and 370B in the vicinity of thesecond linear path segment 388. The distal end of the end 422B thusbears against the rear sidewall of the flat article most recentlyinterposed between a previous article and the stacker belts 370. When asufficient number of flat articles are stacked in the discharge magazine300, the articles exert sufficient force on the second end 422B of thesensor lever arm to cause the sensor lever arm 422 to rotate in theclockwise direction about the pivot post 424. If this clockwise force isgreat enough, the first end 422A of the sensor lever arm will overcomethe bias exerted by the spring 426, and will contact the microswitch430. When so contacted, the microswitch 430 sends an electrical signalto activate the discharge transport drive motor 343. When activated, thedischarge transport drive motor 343 causes the transport belts 342A,342B, 342C carrying flat articles and the compression plate 330 thereonto be transported further in the discharge direction as depicted byarrow 45.

The abutment means 322 of the stacker section 38 has a stripper means440 provided thereon at its end proximate the pulley 376. As shown inFIG. 5, the stripper means 440 is a foot-like member which projectsbeyond the plane of the first exterior wall 332 of the abutment means322. The foot-like stripper member 440 extends between the stacker belts370A and 370B and into the gap 379. The stripper member 440 thus servesto preclude a leading edge of a flat article from being further conveyedby the stacker belts 370 around the pulley 376.

STRUCTURE: PRINTHEAD MOUNT ASSEMBLY

FIGS. 15A and 15B show a printhead mount assembly 500 according to anembodiment of the invention. The printhead mount assembly 500 is locatedat the bar code printer 54 station along the processing-transportsection 24. The printhead mount assembly 500 functions to lock theprinthead 501 of the ink jet printer into a predetermined positionsuitable for the printing operation.

The printhead mount assembly 500 includes an anchor block 502; a bottomclamp member 504; and, a top clamp member 506. The anchor block 502 issecurely fastened to a predominantly planar horizontal surface 508 bytwo fasteners 510.

The bottom clamp member 504 has two yoke legs 512 which straddle theanchor block 502. A pivot rod 514 having threaded ends extends throughaligned apertures in the anchor block 502 and the yoke legs 512. Locknuts 516 are provided on each threaded end of the pivot rod 514. Whenthe lock nuts 516 are loosened, the bottom clamp member 504 can pivotabout the pivot rod 514. Tightening the nuts 516 locks the position ofthe bottom clamp member 504 relative to the anchor block 502.

A tongue 520 of the top clamp member 506 extends downwardly into a spaceformed between the two yoke legs 512 of the bottom clamp member 504. Thetongue 520 is positioned between the two yoke legs 512 by virtue of theextension of a pivot rod 522 through aligned apertures in the two yokelegs 512 and the tongue 520. Like pivot rod 514, the pivot rod 522 hasthreaded ends which receive lock nuts 524. As is understandable by theanalogous description above of the pivot rod 514, the pivot rod 522facilitates pivotal motion of the top clamp member 506 with respect tothe bottom clamp member 504.

The bottom clamp member 504 has a central region 530 which has anessentially truncated, flat-bottomed "V"-shape, as seen in FIG. 15B. Theflat bottom of the central region 530 extends below the surface 508 intoa mating channel suitably shaped to receive region 530. The interior ofthe "V"-shaped central region 530 is partially curved to receive thebottom of the cylindrically-shaped printhead 501.

A distal portion 534 of the bottom clamp member 504 has a pair ofcompression springs 536 sandwiched between the underside thereof and thehorizontal surface 508. At its furtherest extreme, the distal portion534 carries a vertical adjustment means 540. The vertical adjustmentmeans 540 includes an adjustment bolt 542 which extends through thedistal portion 534; through a plastic collar 544; and, into thehorizontal surface 508 where it is threadingly anchored. A threaded locknut 546 is carried on the shaft of the adjustment bolt 542. Movement ofthe lock nut 546 selectively controls the altitude of the lower clampmember 504, and of the entire printhead mount assembly 500, above thesurface 508.

The top clamp member 506 has a central portion 550 which overlies theprinthead 501 clamped therebeneath. A distal portion 552 of the topclamp member 506 carries both a set screw 554 and a fastener 556. Afirst end of the fastener 556 is anchored into the upper surface of thedistal portion of the lower clamp member 504. A second end of thefastener 556 carries a wing nut 558. The set screw 554 has a distal endwhich bears against the upper surface of the distal portion of the lowerclamp member 504.

Adjustment of the adjustment bolt 542 of the vertical adjustment means540 controls the height of the bottom clamp member 504 with respect tothe surface 508. In this respect, adjustment of the bolt 542 permits thebottom clamp member 504 to pivot about the axis of the pivot rod 514.Adjustment of the set screw 554 controls the height of the top clampmember 506 relative to the bottom clamp member 504. In this respect,adjustment of the set crew 554 permits the top clamp member 506 to pivotabout the axis of the pivot rod 522.

As shown in FIG. 15B, the top clamp member 506 has a registration mark560 provided thereon to facilitate the angular orientation of theprinthead 501. In this respect, when the printhead is in a correctposition, a corresponding mark on the printhead lines up with theregistration mark 560 provided on the top clamp member 506. In thismanner, after the printhead 501 has been removed and serviced, theproper angular positioning of the printhead 501 can rapidly bereacquired.

STRUCTURE: READ WINDOW

FIGS. 13A-13C show a read window assembly 570 utilized in conjunctionwith the reader means 50 along the processing/transport section 24. Theread window 570 includes a vertical base member 572 which is anchored tothe planar horizontal surface 508 by fasteners 574. The vertical basemember 572 has a narrow, elongated slot or "read window" 576 formedtherein.

At its top, the vertical base member 572 carries a block 578 and a topextension 579. The block 578 and flange 579 are slightly angled withrespect to the vertical as shown by angle 580. Block 578 has a slotformed therein for a purpose described below, and accommodates a thumbscrew 582 having a shank oriented towards the slot.

A narrow spring steel plate or slide 584 slidably extends behind thevertical base member 572 and through the slot formed in the block 578.The bottom portion of the plate 584 is extruded, or "dimpled" as seenfrom above in FIG. 13C, to fit into the read window 576. The springsteel plate 584 is captivated in the block 578 as the thumb screw 582bears against the plate 584 in the slot of the block 578. Captivity ofthe plate 584 by the block 578 causes the slide to assume an angularorientation at the top of the vertical base member 572. The spring steelplate 584 is painted white. At its very top, the spring steel plate 584has an outwardly-turned flange 585 provided thereon.

The top extension 579 of the vertical member 572 has indicia 586 ofincrements of scale provided therealong. The alignment of the top flange585 of the plate 584 with a particular indicia 586 of the increments ofscale reflects the distance from the bottom edge of an on-edge envelopeto the bottom edge 590 of the plate 584 (that is, the height 592 of theread window as shown in FIG. 13B).

The extruded or dimpled shape of the plate or slide 584 in the readwindow 576 serves to eliminate shadows which otherwise could beerroneously interpreted by the read device as characters. The angularorientation of the slide or plate 584 about the angle 580 advantageouslyeliminates any collision between the slide 584 and envelopes in transit.

STRUCTURE: READ WINDOW SET-UP GUIDE

The read window set-up guide 600 of the embodiment of FIG. 14 isadvantageously provided to assist in the set-up of the read windowassembly 570 of FIGS. 13A-13C. In this regard, the read window set-upguide 600 provides the operator with a simple and quick manner ofdetermining where the top flange 585 of the slide 584 should bepositioned relative to the indicia scale 586 for a certain address fieldon an envelope.

The read window set-up guide 600 is stored behind the keyboard 32, butfor use is slidable from out behind the keyboard 32 to assume theappearance shown in FIG. 14. The read window set-up guide 600 comprisesa transparent, essentially rectangular plastic member 602 mounted on asupport shelf 604. The plastic member 602 has a horizontal scale 606 anda vertical scale 607 provided along bottom and left edges thereof,respectively.

The support shelf 604 also carries a stationary post 608. A sleeve 609extends over the post 608 and has a horizontal, opaque plate 610attached thereto, so that the plate 610 extends over the plastic member602 and parallel to the horizontal scale 606 formed at the bottom edgeof the plastic member 602. The width of the opaque plate 610, i.e. theextent of the plate along the vertical horizontal scale 607, correspondsto the extent of vertical scan of the particular reader employed in thesystem. The positioned of the opaque plate 610 relative to the post 608is selectively lockable by virtue of thumb screw 612. The opaque plate610 carries an arrow-shaped indicator 614 which slides along the plate610 in the horizontal direction.

The read window set-up guide 600 is operated in conjunction with theread window assembly 570 in the following manner. An envelope having theaddress field positioning for a batch is positioned behind thetransparent plastic member 602 of the read window set-up guide 600. Thearrow-shaped indicator 614 is moved to the position of the zip codefield in the envelope address. The opaque plate 610 is slid along post608 so that the plate 610 covers the address field. Numbers on thevertical scale 606 and the horizontal scale 607 can be used to move thetop flange 585 of the sliding spring steel plate 584 of the read windowassembly 570 into corresponding alignment with suitable indicia 586.

OPERATION: FEEDER SECTION

In operation, motors 142 and 156 are turned on ("energized") andenvelopes 86 are placed on-edge on the transport belts 112. With motor156 energized, rollers 75 and 157 continuously rotate in the clockwisedirection. The size of the first stage singulation gap 142 is preset bymanipulating the adjustment screw 155 of the biasing means 152 of thefirst stage singulator means 74. The compression plate 124 is translatedalong guide rod 108 to a point whereat the envelopes 86 are snuglycompressed in a stack between the compression plate 124 at the rear endof the stack and the feeder 72 and the feed assist device 80 at thefront end of the stack. With feed assist carriage 200 in a normaloperating position, the signal on line 246 from feeder switch 244 causesthe signal controller 190 to send signals on line 192 to theclutch/brake mechanism 138 associated with the feeder 72. The signalprompts the clutch/brake mechanism 138 to allow the feeder belt 130 torevolve clockwise around rollers 132 and 134.

Revolution of feeder belt 130 directs the foremost envelope 86A in theinput transport section 24 in the direction of arrow 88 by impartingmomentum to the envelope 86A upon contact of the revolving belt 130 withthe envelope sidewall. The envelope is thus directed to the singulationregion 73.

In the singulation region 73, the envelopes first pass through the firststage singulation gap 142 defined by the first stage singulation means74 and the feeder 72. As an envelope approaches the first stagesingulation means 74, the envelope first contacts the roller 150. If theenvelope is a thicker envelope than that contemplated upon presettingthe first stage singulation gap 142, contact with the roller 150 causesthe lever arm 146 to back away from the feeder 72. That is, the envelopedrives lever arm 146 in the direction opposite the direction depicted byarrow 42, thereby widening the first stage singulation gap 142. Thus,contact of roller 150 by an envelope can serve to displace the stones144A, 144B, and thus temporarily redefine the first stage singulationgap 142 for thick envelopes.

Upon leaving the first stage singulation gap 142, the leading edge of anenvelope heads toward the second stage singulation gap 143 defined bythe rotating pull-out roller 75 and roller 76. The rotating pull-outroller 75 imparts further momentum to the envelope 86, directing theenvelope 86 further in the direction of arrow 88 and into the nip ofcontinuously rotating roller 157 and roller 158.

When the leading edge of an envelope blocks beam 178 between transmitter174 and receiver 176 just upstream from the roller pair 150, 152,receiver 176 sends a signal on line 186 to signal controller 190. Uponreceipt of such signal on line 186, the signal controller 190 applies asignal on line 192 to the clutch/brake mechanism 138 for stopping themotion of feeder belt 130. This braking of feeder belt 130 precludes theimmediate feeding of a further envelope, and thus facilitates a slightdelay and spacing between envelopes.

Continuously rotating roller 157 directs an envelope 86 furtherdownstream toward transport system 62. As mentioned before, transportsystem 62 includes revolving horizontal belt 64 and vertical belts 66and 68. Since the axes 157' and 158' of the rollers 157 and 158 areinclined at angle alpha with respect to the vertical (as shown in FIG.10), the rollers 157 and 158 direct the envelope with a downwardcomponent so that the envelope 86 registers on the horizontal belt 64.The belts 64, 66, and 68 included in the transport system 62 carry theenvelope 86 through the processing/transport section 24 in the directionof arrow 44.

The signal controller 190 turns the clutch/brake mechanism 138 back onat a predetermined time after beam 178 is interrupted. In theillustrated embodiment, the predetermined time is 1/5 second.

Upon emerging from the nip between rollers 157 and 158, the leading edgeof envelope 86 blocks beam 184 between transmitter 180 and receiver 182.When beam 184 is thusly blocked, a signal on line 188 is applied to thesignal controller 190. The signal controller 190 examines the frequencyof the interruptions of beam 178 to determine whether the feeder 72 ishaving difficulty in feeding the next envelope. For example, at a givenspeed of the roller 75, the signal controller knows how many envelopesshould interrupt beam 178 every second. If the controller 190 determinesthat difficulty is experienced by the feeder 72, the signal controller190 applies a signal on line 278 to the feed assist means, and moreparticularly to the assist displacement control means 84.

The signal on line 278 from the signal controller ultimately serves toretract the feed assist means 80 in the direction 42 so that, as shownin FIGS. 11A and 11B, the feeder belt 130 of feeder 72 can bettercontact the next envelope 86 for driving the next envelope in thedirection of arrow 88 toward the singulation region 73. In particular, asignal on line 278 serves to displace the feed assist means 80 from itsnormally biased position as shown in FIG. 11A (wherein the tangent planeT to feeder belt 130 is essentially coplanar to a common tangent planeT' to each of the rollers 220, 222, 224, and 226) to a displacedposition such as that shown in FIG. 11B (whereat the common tangentplane T' is displaced in the direction of arrow 42 from the tangentplane T).

The feed assist means 80 is displaced to a position such as that shownin FIG. 11B in the following manner: The signal applied on line 278causes the output shaft 274 of stepper motor 276 to retract toward post106B. The retraction of output shaft 274 causes rectangular block 252,and switch 254 carried thereon, to move further toward the left as shownin FIG. 4. The signal controller 190 continues to apply signals on line278 until the leftward movement of switch 254 moves feeler arm 258 outof contact with the cam surface 208 of the feed assist carriage 200. Theswitch 254 then applies a signal on line 260 to activate the inputtransport motor 118. Activation of motor 118 drives pulleys 114A, 114B,and 114C, with the result that belts 112A, 112B, and 112C areincrementally advanced in the direction of arrow 42. As the belts 112advance, so do the envelopes 86 and the compression plate 124 carriedthereupon. Advancement of the envelopes 86 and compression plate 124 inthe direction of arrow 42 causes the stack of envelopes 86 to bear withincreasing pressure against the feeder belt 130 and feed assist means 80(particularly against the rollers 220, 222, 224, and 226 which the leadenvelope contacts) until the bias of spring 212 is overcome. When thebias of spring 212 is overcome, the entire feed assist carriage 200 isdisplaced in the direction of arrow 42, with the result that tangentplane T' is no longer co-planar with tangent plane T (see FIG. 11A).When the feed assist carriage 200 is sufficiently retracted so thatfeeler arm 258 of switch 254 again contacts cam surface 208, the switch254 applies a signal on line 260 to deactivate the input transport motor118, and thereby temporarily stop advancement of the belts 112.

With belts 112 stopped and feeder 72 still feeding, pressure against thefeed assist means 80 decreases, with the result that the feed assistcarriage 200 is pulled by bias spring 212 toward its normal biasedposition. In moving toward its normally biased position, feed assistcarriage 200 may again lose contact with the feeler arm 258 of switch254, causing switch 254 to again activate advancement of the transportbelts 112, and thus the envelope stack, toward the feeder 72 and thefeed assist means 80. Pressure then again increases on the feed assistmeans 80, so that the feed assist means 80 is displaced sufficientlythat the feeler arm 258 again rides on cam surface 206 of carriage 200.At that point, the input transport belts 112 again cease incrementation.

The feed assist means 80 including the feed assist carriage 200 thus cancontinuously linearly roam from and return to its normally biasedposition (which is the furthest extent of its permitted travel towardthe input envelope stack), depending on the pressure bearing against thefeed assist means 80. As disclosed above, when the signal controller 190determines that the feeder 72 is having difficulty in feeding a nextenvelope, the assist displacement control means 84 facilitates thefurther displacement of the feed assist means 80 by increasing pressurein the envelope input section. Thus, acting through the assistdisplacement control means 84, the signal controller 190 attempts toovercome difficulties encountered in feeding an envelope, such as athick envelope, by requiring an increase in pressure against the feedassist means 80, thereby necessitating greater displacement of the feedassist means 80 from its normally biased position, and therebyfacilitating enhanced driving force on the difficult envelope.Accordingly, as shown with respect to FIGS. 11A and 11B, the greater thedifficulty encountered in feeding an envelope, the greater the distancebecomes between tangent planes T and T'.

If the feed assist means 80 is displaced so far from the tangent plane Tsuch that the feeding of doubles occur, the signal controller 190 willdetect the feeding of doubles and ultimately cause the feed assist means80 to travel back toward the tangent plane T. In this regard, thefeeding of doubles causes the detector beam 178 to be blocked for a timeperiod longer than that permitted by the signal controller 190. Thesignal controller 190 detects the abnormally long blockage of beam 178,knowing the maximum length of an envelope and the peripheral speed ofthe pull-out roller 75. When an abnormally long blockage occurs, thesignal controller 190 sends a signal on line 278 to extend the outputshaft 274 of the stepper motor 276 away from post 106B. As understoodwith reference to the foregoing description of the retraction of outputshaft 274, the extension of shaft 274 causes the feed assist device totravel in the direction opposite that depicted by arrow 42 (i.e., backtowards the tangent plane T).

The operation of the embodiment of FIG. 9 resembles the operationdescribed above, except that, upon revolution of belt 130', roller 134'essentially kicks belts 130' out of plane T, such that the tangent planeT' of belt 134' is displaced by angle beta as shown in FIGS. 9 and 12.Pivotal movement of the feeder belt 130' in this manner causes theapplication of greater force to the foremost envelope in the inputstack. Upon braking of the feeder 72, the roller 134' resumes its normalpositions, as shown by tangent plane T.

OPERATION: STACKER SECTION

After being processed along the processing path 26 of theprocessing/transport section 24, an envelope is directed on-edge by thehorizontal belt 64 and vertical belts 66, 68 of section 24 toward theintroductory conveying means 302. The path of travel of an envelope Ethorough the stacker section 38 is represented by FIGS. 8A-8E, which areframes representing successive stages of the path of travel.

Upon leaving the processing/transport section 24, as shown in FIG. 8Athe envelope E encounters the O-ring pairs 350, 352 which comprise theintroductory conveying means 302. As the leading edge of the envelope Econtacts the front 0-rings 350A, 350B, and then the rear O-rings 352Aand 352B, the leading edge of the envelope E is deflected from direction44 about the acute angle 362, so that the envelope travels along thelinear introductory path 360.

FIG. 8B shows how the introductory conveying means 302 directs theleading edge of the envelope E along the linear introductory path 360and toward the stacker conveying means 304, and particularly to thestacker belts 370. FIG. 8B also shows that the leading edge of theenvelope E contacts the stacker belts 370.

FIG. 8C shows how the stacker conveying means 304 directs the envelope Eon its edge along the first linear path segment 380 toward the dischargemagazine 300. The stacker belts 370 comprising the stacker conveyingmeans 304 thus deflect the envelope E about the obtuse angle 386 betweenthe linear introductory path 360 and the first linear path segment 380,so that the leading edge of the envelope E is now headed toward thedischarge magazine 300. In particular, the envelope E is now headedtoward the bend point 391 and thus toward the mid-section 382 of apreviously-stacked envelope 384A.

FIG. 8D shows how the stacker conveying means 302 interposes theenvelope E between the previously stacked envelope 384A and the stackerbelts 370. After the leading edge of the envelope E is deflected aroundthe obtuse angle 390 at the bend point 391, the leading edge of envelopeE commences its travel along the second linear path segment 388. Thebending of the envelope E at the bend point 391, as the envelope E isinterposed between the stacker belts 370 and the previously stackedenvelope 384, causes the trailing edge of the envelope E to be displacedthrough the acute angle 392, so that the trailing edge essentially"fishtails" out of the path of the next envelope E'.

This displacement of the trailing edge of the envelope E is facilitatedby the positioning element 394, and particularly the helically threadedfirst portion 394A thereof. In particular, the bottom of the trailingedge of the envelope E is engaged to ride in the helical threads 404 ofthe rapidly rotating positioning element 394, so that the element 394serves to quickly propel the trailing edge of the envelope along thedirection of arrow 45, even before the envelope E encounters thedischarge belts 342 and while the leading edge of the envelope E isheading up the second linear path segment 388. Indeed, with the trailingedge of the envelope E experiencing a component of motion in thedirection of arrow 45, and the leading edge having a component of motionin the opposite direction (i.e., back up to pulley 376), it isunderstood how the fishtailing is facilitated. After its trailing edgeis displaced through the acute angle 392, the envelope E then regainsits linear profile which, as illustrated in FIG. 8E, is colinear withthe second linear path segment 388.

It should be noted that the length of the first linear path segment 380is sufficiently long such that, when the trailing edge of an envelope Eis displaced or fishtailed through the angle 392, the trailing edge ofenvelope E does not strike the pulley 356, i.e. does not cross thelinear introductory path 360.

FIG. 8E further shows how the envelope E settles in the stack formed bythe discharge magazine 300. In particular, envelope E is situated sothat as its front sidewall contacts the previously stacked envelope384A, its rear sidewall contacts the moving stacker belts 370. Theleading edge of envelope E then abuts the magazine abutment means 322.Stripper member 440 formed on the abutment means 322 precludes theleading edge of envelope E from travelling further along with thestacker belts 370, so that the envelope E is retained in the dischargemagazine.

As the envelope E strikes the abutment means 322, what would otherwisebe an audibly noticeable popping sound is muffled by the acousticinsulation material 338 provided in the internal cavity 336 of theabutment wall 322.

FIG. 8E also shows what happens when the discharge magazine 300 becomessufficiently loaded with envelopes, i.e., when enough envelopes becomeinterposed between the stacker belts 370 and the compression plate 330that the discharge transport belts 342 need to be activated to carry theenvelopes and compression plate 330 further away from the stackersection 38 in the direction of arrow 45. The stack of envelopes in themagazine 300, acting through the rear sidewall of envelope E, exertssufficient force F on the second end 422B of the sensor lever arm tocause the sensor lever arm to pivot in the clockwise sense about thepivot post 428. If the force F is sufficiently great to overcome thebias on the first end 422A of the sensor lever arm provided by thespring 426, the first end 422A of the sensor lever arm will trip themicroswitch 430. When the microswitch 430 is so tripped, the microswitch430 sends an electrical signal to activate the discharge transport drivemotor 433. When activated, the discharge transport drive motor 433drives pulleys and the discharge transport belts 342 entrainedthereabout, so that the belts 342 and the envelopes and compressionplate 330 riding thereon are transported further away from the stackersection 38 in the direction depicted by arrow 45, with the result thatthe stack becomes less tight for accommodating further envelopes.

As the envelopes stacked in the discharge magazine 300 are transportedaway from the stacker section 38 in the direction of arrow 45, theleading edges thereof contact the ridges 340 provided on the magazineabutment wall 322. The ridges 340 essentially serve as bearing points toreduce the frictional drag between the envelopes and the abutment wall322, with the result that envelopes are less susceptible to snagging orjamming in the magazine 300.

The positioning element 394 also continues to optimally position theenvelopes in the discharge magazine 300. The second portion 394B of theelement, also being rotatably driven, periodically elevates the bottomedges of envelopes riding thereon so that the envelopes become properlyregistered against the abutment wall 322. In this regard, and as shownin FIG. 6, when the chord-like surfaces 406 of the element 394 areparallel with the horizontal, the element 394 is substantially planarwith the magazine floor 320. However, when the arcuate surfaces 408 ofthe member 394 are positioned to protrude through the slot 398 formed inthe magazine floor 320, the bottom edges of the envelopes are elevated,with the result that the bottom edges of the envelopes become inclinedat the angle 410 with respect to the magazine floor 320.

While the invention has been particularly shown and described withreference to the preferred embodiments thereof, it will be understood bythose skilled in the art that various alterations in form and detail maybe made therein without departing from the spirit and scope of theinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. An apparatus formounting a printhead relative to a horizontal surface, said apparatuscomprising:an anchor block mounted on said horizontal surface; a bottomclamp member, said bottom clamp member having a first region pivotallyattached to said anchor block at a first pivot axis, a central regionfor contacting at least a part of said printhead, and a distal region;vertical adjustment means connected to said distal region of said bottomclamp member for pivoting the bottom clamp member about the first axisto adjust the vertical height of said bottom clamp member relative tosaid horizontal surface; a top clamp member for sandwiching saidprinthead between said bottom clamp member and said top clamp member,said top clamp member being pivotally connected to said bottom clampmember at a second pivot axis distinct from the first pivot axis.
 2. Theapparatus of claim 1, wherein said bottom clamp member has at least onecompression spring sandwiched between the underside thereof and saidhorizontal surface.
 3. The apparatus of claim 1, further comprisingmeans for locking said bottom clamp member relative to said anchorblock.
 4. The apparatus of claim 1, wherein said first region of saidbottom clamp member comprises two yoke legs pivotally connected to saidanchor block at said first pivot axis; wherein a pivot rod extendsbetween said two yoke legs of said bottom clamp member for forming saidsecond pivot axis; and, wherein said top clamp member is pivotal aboutsaid pivot rod extending between said two yoke legs of said bottom clampmember.
 5. The apparatus of claim 4, further comprising means foradjusting the height of the top clamp member relative to the bottomclamp member, said means for adjusting the height of the top clampmember relative to the bottom clamp member comprising a set screw, withthe adjustment of said set screw permitting the top clamp member topivot about said pivot rod.
 6. The apparatus of claim 1, wherein saidtop clamp member has a first portion which is pivotally connected tosaid bottom clamp member; a central portion which overlies a printheadsandwiched therebeneath; and, a distal portion; further comprisinganchoring means for anchoring the distal portion of the top clamp memberto the distal region of said bottom clamp member.
 7. The apparatus ofclaim 1, further comprising means for adjusting the height o the topclamp member relative to the bottom clamp member.
 8. The apparatus ofclaim 1, wherein at least one of said clamp members has a registrationmark provided thereon to facilitate angular positioning of theprinthead.
 9. The apparatus of claim 8, wherein said top clamp memberhas a registration mark provided thereon to facilitate angularpositioning of the printhead.
 10. An apparatus for mounting a printheadrelative to a horizontal surface, said apparatus comprising:an anchorblock mounted on said horizontal surface; a bottom clamp member, saidbottom clamp member having a first region pivotally attached to saidanchor block at a first pivot axis, a central region for contacting atleast a part of said printhead, and a distal region; vertical adjustmentmeans connected to said distal region of said bottom clamp member foradjusting the vertical height of said bottom clamp member relative tosaid horizontal surface; a top clamp member for sandwiching saidprinthead between said bottom clamp member and said top clamp member,said top clamp member being pivotally connected to said bottom clampmember at a second pivot axis; wherein said first region of said bottomclamp member comprises two yoke legs pivotally connected to said anchorblock at said first pivot axis; wherein a pivot rod extends between saidtwo yoke legs of said bottom clamp member for forming said second pivotaxis; and, wherein said top clamp member is pivotal about said pivot rodextending between said two yoke legs of said bottom clamp member meansfor locking said bottom clamp member relative to said anchor block;means for adjusting the height of the top clamp member relative to thebottom clamp member.